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  • PHOENICS Overview; TR 001
    and line printer plot form It is the Q1 file with which the user has most to do whether it is taken from the extensive Input File library which forms part of the PHOENICS installation or created by way of a text editor perhaps as a modification of a library file or created as part of an interactive SATELLITE session in which the user enters PIL statements at the keyboard and is assisted to do so correctly by acceptance and non acceptance responses or created without the user s needing knowledge of PIL by way of the VR Editor with its associated menu system However it is written the content of the Q1 file is what dictates how the flow simulating calculation will proceed 3 3 Auxiliary modules SATELLITE EARTH and PHOTON can be run by issuing the appropriate commands sat ear or pho at the command line of DOS or Unix or by double clicking on the appropriate line of the Windows desktop CHAM has however also provided for the convenience of users other means of activating the programs either individually or in sequence These are the PHOENICS Commander and the PHOENICS Environment The feature which is common to both modules is that they allow PHOENICS actions to be initiated by way of mouse clicks thus relieving the user from remembering and then typing the names of the commands Their disadvantage is that they force the user to wait while they are starting up and of course to navigate to the right decision making point Further comments about them are The Commander is the newest replacing both the Manager which made its appearance in PHOENICS 3 4 and a much older environment module which was also called Commander It is the choice of necessity for Unix The Environment is of intermediate age and it also works only for Windows 98 2000 NT XP It is in fact an enhanced SATELLITE module working in VR Editor mode There are other modules which in this overview document it is appropriate to mention only in passing They are ShapeMaker which facilitates the creation of faceted objects around which flow can be computed and which can also be displayed visually in the Virtual Reality interface AC3D which is a third party 3D modeller program bundled with PHOENICS which can also create facetted objects for the Virtual Reality interface Facet Fixer a utility which creates dat files suitable for use with the PHOENICS Virtual Reality User Interface from possibly defective STL files produced by CAD and architectural packages the PLANT Menu which facilitates the selection and creation of formulae which are to be automatically translated into Fortran by the PLANT feature of the SATELLITE and other utilities for compressing or filleting data files 3 4 Additional files Other files of importance in alphabetical order include CHAM INI into which users can insert decisions about modes of operation which they wish only seldom to modify CONFIG which contains the crucial unlocking string FACETDAT which is created by SATELLITE and which contains the geometrical information about the those objects which are described by way of facets GROUND HTM a Fortran file which is accessible to users and contains slots for the introduction of the user s own coding sequences PHOLOG which records the key strokes made during a PHOTON session in case they need to be repeated PBCL DAT which is created by EARTH and which is used for recording information useful for displaying results about partially blocked cells Q1EAR which is created at the end of a SATELLITE run and which records in standardised format all the implications of the Q1 file for a particular run Q2 which being read by SATELLITE after Q1 and if it takes place the interactive session can contain the user s after thoughts U from which PHOTON can read display eliciting commands XYZ which contains the co ordinates of all cell corners of a body fitted coordinate grid direct access forms of the sequential files PHI and XYZ namely PHIDA and XYZDA Information about some of these will be supplied later in this document and all of them are described in the PHOENICS Encyclopaedia 3 5 The options For reasons which are now mainly historical the coding and the input file libraries of the EARTH i e solver module of PHOENICS are arranged in segments called options Newcomers to PHOENICS are bound to encounter some mention of the options and may suppose their existence to be more important than it is Therefore the following account is provided The original purpose of options was to enable purchasers of PHOENICS licences to reduce their expenditure by taking the core but none or few of the options Nowadays all options are supplied always The names of the options are advanced multiphase body fitted coordinate advanced chemistry GENTRA particle tracking multi block and fine grid embedding multi fluid advanced algorithms PLANT fortranizer advanced radiation simultaneous solid stress advanced turbulence two phase wherein the word advanced is used when the core already includes some capabilities of the kind indicated Correspondingly the d earth directory of PHOENICS has d core d opt and somewhat anomalously d vr sub directories d core contains open source Fortran files and a sub directory called INPLIB which contains the core input library files d opt contains sub directories d advmph d bfc d chem d gentra d mbfgem d mfm d numalg d mig d plant d rad d solstr d turb d twophs each of these sub directories contains or may contain open source Fortran files and each also contains a sub directory called INPLIB d vr contains only a sub directory called INPLIB which holds many but not all of the library cases which were created by means of the VR Editor As far as the coding is concerned these names do indicate where the relevant Fortran files are to be found However the correspondence between the option names and the contents of the input files is much less direct for the simple reason that practically interesting flow simulations often involve several optional features for example two phase flow and combustion and body fitted coordinates 4 Modes of operation 4 1 Distinguishing the modes PHOENICS modules can be operated in various manners the choice of which depends on the user s personal preference experience and current needs and circumstances The following remarks which are intended to facilitate the proper choice for the problem in hand are organised under the headings command Q1 editing text interactive menu interactive PLANT using own Fortran using input from CAD input from grid generation packages output to third party graphics packages mixed 4 2 The command mode By command mode is meant the entering of commands at the DOS or UNIX prompt by way of the keyboard no other response being expected but that of execution The command mode is appropriate for what might be called production runs i e those flow simulating calculations for which the input data have already been determined and are embodied in identified Q1 files the nature of the required output has also been settled and is expressed either in the Q1s themselves or in macros i e U files for PHOTON there is no requirement for the user to intervene in the calculation process This mode is preferred by users who perhaps having spent some day time hours preparing a series of Q1s wish to have the runs executed overnight possibly by way of the PHOENICS multi run facility CHAM s quality control procedures for example entail the performance of many hundreds of such test battery runs each night followed by comparison of the results with those which are expected so as to detect whether any change made to the software has had an inadvertent consequence However newcomers to PHOENICS may also wish to use the command mode at the start confining themselves to executing ready to run cases or active demos via the Commander or Environment The command mode is also appropriate when the COSP constant optimising procedure is in use for this involves running the EARTH solver module in perpetuum mobile mode until the sought for goal has been attained The commands supplied with the PHOENICS installation are described in the scripts entry of the PHOENICS Encyclopaedia but the user is of course free to embody these into others which he or she prefers 4 3 The Q1 editing mode What happens in a flow simulating calculation made by PHOENICS is as has been already stated entirely controlled by the contents of the Q1 file expressed via the PHOENICS Input Language PIL Many users especially those having months or years of experience therefore prefer to take full control of the calculation by writing the Q1 for themselves However even new or infrequent users who are likely to prefer one of the interactive modes of operation may like to know that these modes are there only to make Q1 writing easy The merits of the Q1 editing mode of operation are speed especially if the required Q1 can be created by making minor changes to one which has been used successfully before for example one of the many hundreds in the PHOENICS Input File libraries supplied with the installation certainty that no well meant but inappropriate settings made by the writers of the menus can have over written what the user intended freedom for the user to employ his or her personal style and to include helpful annotations the ability to exploit the numerous features of PIL which cannot be introduced interactively for example DO loops IF THEN ELSE constructs file handling statements such as INCL and INTRPT DISPLAY ENDDIS PHOTON USE ENDUSE GOTO LABEL READVDU MESG The wide range of commands which are associated with In Form the powerful new Input of FORMula feature and many others The disadvantage of course is that knowledge of PIL is needed and this can be only gradually acquired However those who intend to become serious long term users of PHOENICS and to exploit more than the most superficial of its flow simulating capabilities should recognise that they may need to master at least the rudiments of PIL for the VR Editor can not do everything for them Full information about PIL can be found in the PHOENICS Encyclopaedia There also exist some PIL tutorials It may be remarked that the Q1 editing mode can also control the subsequent running of PHOTON for this is so programmed that if there exists in the local directory a file called u or U it will take instructions from it Then if that file contains simply the line USE Q1 PHOTON will look in the Q1 file for and obey instructions between the lines PHOTON USE and ENDUSE Many input library Q1s contain such PHOTON instruction sequences The VR Viewer can also use such Q1 files as macros to display a similar sequence of images 4 4 The text interactive mode The PHOENICS SATELLITE module can be caused to run in such a mode that once the existing Q1 has been interpreted the program awaits the entry of further PIL statements by way of the keyboard The relevant commands are txt The new statements if they contain no errors are then accepted as augmenting or replacing the existing statements and they are added to the end of the Q1 file If the new statements infringe the rules of PIL in some way they are rejected then an explanation of the reason for rejection appears on the screen The text mode SATELLITE also permits the introduction modification or deletion of lines which are not immediately interpreted for it has its own built in Q1 editor Therefore what has been said above about the inability of the interactive mode to introduce DO loops and other features is somewhat too strong for they can be introduced via the built in editor in text interactive mode However most users nowadays prefer to use a stand alone text editor for creating all but the simplest Q1s It should be remarked that PHOTON can also be run in text interactive mode which is indeed the default Commands typed at the keyboard so long as they are among those recognised by PHOTON are responded to immediately A list of such commands is provided by the PHOTON HELP file PHOTON also has the facility to record the user s actions in a pholog file which can be later hand edited and re named as a u macro Similarly the VR Viewer can save a macro file which can then be used to re create the same image from another data set These facilities are valuable because of their person time saving potential Interacting with a graphical display package is often enjoyable but since humans cost more than computers it can be the most expensive part of a CFD using operation 4 5 The menu interactive mode The second method of interactive problem specification is via the SATELLITE menu which is usually but not necessarily associated with the use of the VR Editor the latter represents visually what the already accepted data are This mode can be entered from the DOS or UNIX command prompts from the text interactive mode by issue of the appropriate PIL commands from the Commander or Environment by clicking on the appropriate buttons The advantage of using this mode is that some settings are made by simple mouse clicks and others by typing numbers into boxes so it can be used by those who have no knowledge of the nature or meaning of PIL variables or the syntax of the statements which set their values The disadvantage is as already mentioned that only a sub set of the desirable PIL settings can be made in this way and moreover not only can logic using PIL statements such as DO loops not be inserted those which are already present in the Q1 when the interactive session starts will be omitted from the Q1 which is finally written The use of this mode of problem specification is described in TR 324 for beginners and in TR 326 for more advanced users PHOTON also can be operated in menu mode as well as text mode This is convenient for users who do not remember or have never learned what are the commands which PHOTON otherwise needs The VR Viewer which is the alternative results display module and which has the merit of giving the flow domain an appearance which is wholly compatible with that presented by the VR Editor can be operated in menu mode or it can read commands from a macro file 4 6 The PLANT using mode For those users a diminishing proportion it may be remarked who find the already described methods of problem specification insufficient the next recourse is to introduce PLANT formulae into the Q1 files and so allow the SATELLITE to interpret them convert them into their Fortran equivalents and write the corresponding GROUND file Thereafter the file is compiled the new EARTH executable built and the run executed without further user intervention The PLANT lines can be introduced into the Q1 file in either of two ways namely direct editing which requires some acquaintance with PLANT formula terminology and syntax and interaction with the PLANT menu utility which does not 4 7 The own Fortran using mode There do exist PHOENICS users who would rather introduce their own Fortran coding than find out whether or how what they want can be provided by PLANT Such users need to learn how GROUND coding interacts with EARTH but this is not difficult because the extensive open source components of PHOENICS provide many examples which users can follow Further PHOENICS is equipped with numerous service subroutines calls to which can be incorporated into the user s coding The relevant entry in the PHOENICS Encyclopaedia provides further explanations and examples 4 8 Input from CAD Very often CFD analysis is required for a situation which has been already defined geometrically by way of a Computer Aided Drawing CAD package The definition is then usually expressed by way of one or more STL or DXF files which it is necessary to import into PHOENICS This task is made extremely easy for the user because The PHOENICS SATELLITE is itself able to read STL and DXF files and to convert them into the format which it employs for display in its Virtual Reality Editor and Viewer The details of how this is done are explained in the PHOENICS VR Reference Guide TR 326 Below is shown an example of residential buildings displayed in the VR Editor The CAD file was created by way of the well known AUTOCAD package This CAD file in STL format was polished by PHOENICS and then imported into PHOENICS VR in a few seconds rotated and somewhat re sized 4 9 Input from grid generation packages The PHOENICS SATELLITE has its own several ways of creating body fitted coordinate grids and such grids can be created also via PLANT or by means of user created Fortran coding attached to EARTH However some users prefer to use a third party grid generation package PHOENICS also is equipped with GENIE its own Generic Interfacing Environment which is capable of converting grids created by other packages into PHOENICS usable format GENIE can also convert PHI files produced by PHOENICS into formats usable by third party graphics packages 4 10 Output to graphics display packages Typical of the third party graphics packages with which PHOENICS can interact is TECPLOT The following picture shows streamlines in a duct into which flow two streams from transverse ducts The computational grid was created with the aid of GeoGrid PHOENICS was used in multi block mode and the graphics display was prepared by means of TECPLOT 4 11 The mixed mode There is no mixed mode as such This section is therefore provided simply as a place for stating that experienced users of PHOENICS rarely use one mode only and that they are certainly not forced to do so by PHOENICS Indeed users of PHOENICS are more likely to complain about the over large range of different ways which PHOENICS offers for doing essentially the same thing It is for this reason that section 4 of the document has been provided 5 Getting started By way of 2008 update This was written before PRELUDE had come into being Now a PRELUDE icon Chopin s head should be visible and a good way to get started would be to click on it and then to work through some of the tutorials accessed by clicking help the PHOENICS Commander the VR Editor the command mode Preliminary note After installation of PHOENICS four icons should be present on the desk top entitled PHOENICS Commander PHOENICS VR WINDF POLIS The first three correspond to the next three sub section of this document the fourth leads to the main on line information source about PHOENICS of which the Encyclopaedia is the most often used 5 1 Getting started via the PHOENICS Commander The easiest way to get started is to activate the PHOENICS Commander either by clicking on the desk top icon created at installation time or by entering the command pc at the command prompt What should then appear on the screen is something like for refinements are constantly being introduced this The screen messages explain the functions which each button leads to It is re printed below The buttons along the top edge provide access to the PHOENICS Computational Fluid Dynamics Software Package Specifically The New User button will lead you to a page designed for beginners which enables them to learn about PHOENICS to see it in action and to test drive it About PHOENICS opens up the full treasury of information about the nature and capabilities of the software Input File Libraries leads to many hundreds of flow simulation cases which you can run for yourself with such modifications as you care to introduce Run modules enables you when you are ready to run individual modules of the package without either restriction or close guidance Edit Files enables you to inspect or modify those files of the PHOENICS package which interest you The buttons on the left are Display Options to change colour font and other visual features of the Commander Enable Editing to bring an edit page button into view This enables you to modify if you wish the page which you are looking at Choose Working Directory i e the folder containg the files you are working with Most users prefer to create a different working directory for each project The default working directory is phoenics d privpc Choose Versions if alternatives exist Run vre to run the PHOENICS VR Environment module This is provided for experienced users of PHOENICS who will probably wish to use the next button also Ready to run a selection of ready to run cases from the input file library arranged so as to enable you to run Satellite for the input of data EARTH for running the executable and PHOTON or Viewer for graphical display of results New users are strongly advised to advised to press the new user button whereupon they should see a screen like this Quick start is there for the impatient slower start for the more cautious and tutorials for those who are desire even more guidance Thereafter judicious choice of ready to run cases will provide an excellent preparation for later work with PHOENICS 5 2 Getting started via the VR Editor If the just described Commander route has been fully explored the PHOENICS Virtual Reality interface will already have been encountered and exercised However an alternative and more varied approach is to proceed by studying the document TR 324 Starting with PHOENICS VR which is accessible by way of the POLIS button and the documentation and hard copy documentation links to which it leads Those proceeding by this route are advised either to follow the instructions printed in the hard copy version of the document if they have one or to do so by keeping its electronic copy open in a separate window A warning should be expressed at this juncture despite the many things that the VR Editor can do it cannot unleash the full potential of PHOENICS Since newcomers to PHOENICS often have the desire to embark immediately on some very ambitious flow simulation tasks they are sometimes disappointed to discover that these cannot be launched from the VR Editor They will then need to dig a little deeper into the documentation helped if they so request by CHAM s user support team in order to learn how the PHOENICS Input Language and especially its In Form and PLANT features will enable them to achieve their objectives They can however rest assured that there are few known flow simulation problems which PHOENICS can not solve 5 3 Getting started via the command mode Those users who prefer always to be in complete control of what they are doing may prefer to start at the command prompt and issue simple commands only until their confidence has grown sufficiently to allow more complex ones The DOS command prompt can be brought to the screen by double clicking the windf icon the name of which stands rather inappropriately for Windows Digital Fortran The working directory should then be found to be phoenics d priv1 Users whose practice it is to employ such auxiliary programs as The Norton Commander or FAR may find it convenient to activate one of them at this point But this is not essential If the installation has been fully successful the path associated with the Window should include phoenics d utils and phoenics d utils d windf However if it does not the full path name alternatives to the commands mentioned below should be employed a A do nothing run In order to start the VR Editor in command mode the command to issue is modq1 which places a model Q1 file in the local directory The DOS DIR command will reveal whether it is present If it is not try typing the full path name of the command which is phoenics d utils modq1 The command edit q1 will show the content of this file exhibiting the standardised data group structure of PHOENICS but making no non default data settings whatsoever A suitable command to issue next is txt full path name phoenics d utils d windf txt which activates the SATELLITE module in text interactive mode The resulting screen image is as follows This gives the user an opportunity to enter data but if the opportunity is not taken and the session is immediately terminated it will be found that the Q1 file has been left unchanged a Q1EAR file has been created in which all the settings are the defaults and that an EARDAT file has been created of which the same is true If then the command ear is issued the solver module EARTH will run but it will terminate very quickly producing a RESULT file of which the small content indicates that no simulation has actually been performed b Exploring the text interactive SATELLITE If the process is repeated but this time the opportunity to insert data interactively is taken the methodical explorer will probably proceed in small steps for example as follows Pressing function key 2 will cause the command mode to be entered Entering NX will elicit the response NX 1 which is the default value of the number of grid intervals in the x direction Entering NX 10 will set the value of that quantity correspondingly This can be confirmed by entering NX to which the screen s response will be NX 10 Entering SOLVED will elicit a screen response which indicates that no variables are being solved Entering SOLVE P1 followed by SOLVED will produce a screen message which indicates that P1 which is the first phase pressure variable is being solved These actions will have altered the Q1 file the bottom of which can be seen by entering LB with the result that the screen shows NX 10 SOLVE P1 In this way step by step a complete Q1 can be built up however short cuts can be taken Thus by entering LOAD 100 the user can cause the Q1 to be augmented by the complete set of commands which constitute core library case 100 Thereafter he or she can determine what the settings are by entering the names of the variables make settings by entering variable name value by using the built in editor and the I for insert L for list and D for delete commands make more elaborate modifications This is not the place for a comprehensive presentation of the PHOENICS Input Language PIL However enough has perhaps been written to indicate its general character and the way in which the PHOENICS SATELLITE responds to it c Exploring the menu interactive SATELLITE If the command m2 is entered at the command prompt the SATELLITE is activated in menu 2 mode What then appears on the screen is as shown below It is the top panel of the menu which is associated with but is distinct from the VR editor The exploration minded user will wish to click on the buttons at the top of the panel so as to access deeper levels at which settings can be made by mouse clicks or the typing in of numbers Then having returned to click on OK he or she will quit the program and thereafter examine the Q1 and Q1EAR files which have been created It will be observed from the above image that this menu does allow a library case to be loaded if its number is known Then the settings made by it are displayed in the appropriate boxes of the menu and can be altered by the user ear thereafter launches an EARTH run as before Then pho launches a PHOTON run and vrv activates the VR Viewer 6 Physical and mathematical content of PHOENICS 6 1 Conventional features PHOENICS has all the features which are common to commercial CFD codes indeed it pioneered them Since the present document is an overview rather than a text book it has been judged sufficient here simply to list the conventional features under two headings namely physical and mathematical Thereafter some of the less conventional features of PHOENICS will be given more attention a Physical PHOENICS simulates flow phenomena which are laminar or turbulent compressible or incompressible steady or unsteady chemically inert or reactive single or multi phase in respect of thermal radiation transparent participating by way of absorption and emission participating by way of scattering The space in which the fluid flows may be empty of solids or wholly or partially filled by finely divided solids at rest as in porous medium flows or partially occupied by solids which are not small compared with the size of the local computational cells In the latter two cases the solids may interact thermally with the solids that is to say that PHOENICS can handle conjugate heat transfer Such immersed solids can also participate in radiative heat transfer The thermally and mechanically induced stresses and strains in the immersed solids can also be computed by PHOENICS The thermodynamic transport including radiative chemical and other properties of the fluids and solids may be of arbitrary complexity b Mathematical Click here for a more extended treatment The equations solved by PHOENICS are those which express the balances of mass momentum energy material ie chemical species other conserved entities e g electrical charge over discrete elements of space and time i e finite volumes known as cells The cells are arranged in an orderly i e structured manner in a grid which may be cartesian cylindrical polar or body fitted i e arbitrarily curvi linear and which may be segmented into distinct blocks 2008 update Since 2006 PHOENICS has had additionally an unstructured option namely USP UnStructured PHOENICS A description is to be found by clicking here These equations express the influences of diffusion including viscous action and heat conduction convection variation with time sources and sinks In order to reduce the numerical errors which may result from the unsymmetrical nature of the convection terms PHOENICS can make use of a large variety of higher order schemes including QUICK SMART Van Leer and many others The dependent variables of these equations are thus mass or volume fraction velocity and pressure temperature or enthalpy concentration electrical charge or other conserved property The mass and momentum equations are solved in a semi coupled manner by a variant of the well known SIMPLE algorithm Because the whole equation system is non linear the solution procedure is iterative consisting of the steps of computing the imbalances of each of the above entities for each cell computing the coefficients of linear ised equations which represent how the imbalances will change as a consequence of small changes to the solved for variables solving the linear equations correcting the values of solved for variables and of auxiliary ones such as fluid properties which depend upon them repeating the cycle of operations until the changes made to the variables are sufficiently small Various techniques are used for solving the linear equations including tri diagonal matrix algorithm a variant of Stone s Strongly Implicit Algorithm conjugate gradient and conjugate residual solvers 6 2 Simulation of multi phase flow in PHOENICS Multi phase flows are those involving to name but a few examples steam and water in a boiler air and sand in a desert storm fuel droplets and combustion gases in an engine a layer of oil floating on the surface of a river If on line click here to see an example PHOENICS was the first general purpose computer code to be able to simulate multi phase flows and it is still capable of doing so more effectively and in a greater variety of ways than most of its competitors Multi phase flow phenomena can be simulated by PHOENICS in four distinct ways These are as two inter penetrating continua each having at every point in the space time domain under consideration its own velocity components temperature composition density viscosity volume fraction etc as multiple inter penetrating continua having the same range of properties as two non interpenetrating continua separated by a free surface If on line click here to see an example or as a particulate phase for which the particle trajectories are computed as they move through a continuous fluid Details of how PHOENICS performs its simulations can be discovered by on line viewers by clicking on the above links to the PHOENICS Encyclopaedia 6 3 Turbulence models in PHOENICS Why turbulence models are used The flows which PHOENICS is called upon to simulate are more often than not turbulent by which is meant that they exhibit near random fluctuations the time scale of which is very small compared with the time scale of the mean flow and of which the distance scale is small compared with the dimensions of the domain under study Since the beginning of the practice of computational fluid dynamics in the 1960 s the impracticability or more precisely the prohibitive expense of predicting these fluctuations has resulted in the invention of turbulence models which represent to some extent their results The subject is too large to deal with in this Overview but the lectures and other documentation provided with the PHOENICS package contain much information Typical is the lecture entitled Turbulence models for CFD in the 21st Century Satisfactoriness A broad brush summary of the satisfactoriness of the most widely used turbulence models is for predicting time average hydrodynamic phenomena and the macro mixing of fluids marked by conserved scalars the models are not bad but for the simulation of micro mixing which is essential if chemical reaction rates are to be predicted they are very poor indeed and the most distressing aspect of the last mentioned point is that it is not sufficiently recognised by the users of the models Turbulence models in PHOENICS PHOENICS is particularly rich in turbulence models as can be seen from the relevant Encyclopaedia Entry Two of these are of special interest because they are unique to PHOENICS namely The LVEL model is most useful in circumstances in which many solids are immersed in the fluid making conventional two equation models impractical It handles the complete range of Reynolds number smoothly and it contains its own unique and simple method for calculating the distances to and between walls If on line click here to see an example The Multi Fluid Model MFM possesses more radical novelty for it provides a direct means of computing the quantities of practical importance so supplanting the conventional indirect means MFM is especially useful for simulating turbulent combustion processes about which several lectures are supplied with the PHOENICS package for example this and this 6 4 Radiative heat transfer models in PHOENICS PHOENICS is supplied with several means of computing thermal radiation all of which are described in the PHOENICS Encyclopaedia Entry A method which is unique to PHOENICS and is especially convenient when radiating surfaces are so numerous and variously arranged that the use of the view factor type model is impractically expensive is IMMERSOL If on line click here to see an example This method is computationally inexpensive capable of handling the whole range of conditions from optically thin ie transparent to optically thick ie opaque media mathematically exact when the geometry is simple and never grossly inaccurate even when it is not examples of its use may be seen by clicking here IMMERSOL is particularly useful for electronics cooling problems and is an important feature of HOTBOX 6 5 Chemical reaction processes in PHOENICS From its beginning in 1981 PHOENICS has been used for

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  • In-Form; TR 003
    of Technical Report 003 is a Word document containing the text of the PHOENICS Encyclopaedia article on In Form without however any of the graphical illustrations It has been included

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  • Material Properties in PHOENICS; TR 004
    and chance of phase provided that it is supplied with information about the properties of the materials which are involved PHOENICS has several channels for such information Some are old and some are new some are convenient for one purpose and some for another The present document has been added to the hard copy documentation so as to assist users to make the choice best suited to their needs It

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  • TR/324: Starting With PHOENICS-VR
    Top menu Click on OK Figure 7 The Turbulence Models page of the Main Menu Now the user should have returned to the main VR Editor screen and the graphics screen should look like figure 8 If the image does not appear correct click on the pull down arrow next to the R icon on the toolbar then Fit to window Figure 8 The domain with its size set b Next create the first object which will act as a blockage in the flow domain To create a fence across the flow domain in the y direction Click on the button on the Control panel or on the toolbar this will open the Object management panel OMP From the Object menu choose the option New New object A new object will then be created at the origin of the domain and the object dialog will be opened This will display the dialog box shown in figure 9 Figure 9 The Object dialog Box Change name to FENCE Go to the dialog page titled Size set the size of object as X 0 1 Y tick To end Z 0 25 Now go to the dialog page titled Place set the position of object as X 0 3 Y 0 0 Z 0 0 Return now to the General dialog page Define TYPE BLOCKAGE default To set the material properties for the fence click on ATTRIBUTES click on Other Materials then on SOLIDS then OK followed by ALUMINIUM and OK Click on OK to return to the Object dialog Box and then on OK to close the Object dialog Box The VR Editor screen should appear as in figure 10 Figure 10 The fence object c Now create another object which will serve as an additional blockage in the flow domain To create a blockage in the form of a cylinder do the following From OMP choose the menu item New Object Change name to CYL Go to the dialog page titled Size set the size of object as X 0 1 Y 0 1 Z tick To end Now go to the dialog page titled Place set the position of object as X 0 0 Y 0 0 Z 0 0 Next Go to the dialog page titled Shape In Geometry select PUBLIC SHAPES CYLINDER JPG and click OK on the Geometry Import dialog which opens Return now to the General dialog page Define TYPE blockage default To set the material properties for the cylinder Click on ATTRIBUTES Other materials OK SOLIDS OK followed by ALUMINIUM and OK Click on OK to return to the Object dialog Box and then on OK to close the Object dialog Box The VR Editor screen should appear as in figure 11 Figure 11 The fence and cylinder objects d Next an array of cylinders will be created from the first cylinder First the cylinder just created will be used to make two more cylinders for a total of three To accomplish this The cylinder should already be the current object it should be outlined in white and highlighted in the OMP If it is not click on it in the VR Editor graphics window or the OMP The outline of the cylinder facets will turn white indicating that it has been selected for further editing Click on the Duplicate using array button on the hand set see figure 3b or window tool bar and set DIMENSION and PITCH as Direction Dimension Pitch X 1 0 0 Y 3 0 4 Z 1 0 0 DIMENSION is the number of repetitions in a direction PITCH is the distance between origins Click on OK Three cylinders should now appear in place of the original cylinder in the graphics window as shown in figure 12 Figure 12 The three cylinder objects Now the three cylinders will be grouped so they can be moved together At this point the final object in the array CYL 4 should now be highlighted in the Object management panel To create the group highlight the objects from CYL through to CYL 4 This is done through familiar windows techniques while CYL 4 is highlighted hold the shift key down then click on the line containing CYL This should then highlight all the lines and hence objects between these two objects The current group consists of the highlighted objects See figure 12a Figure 12a The three cylinder objects grouped The group may be move to a specified location by entering a new position on the control panel see figure 3b Set the X position to 0 60 and Y position to 0 04 The geometry should now look as in figure 13 Figure 13 The array of cylinders moved to new position e Next an inlet to the flow domain will be created To create an inlet to the domain From OMP choose the menu item New Object Change name to INLET Set the size of object as X 0 0 Y tick To end Z tick To end Go to the dialog page titled Place Set the position of object as X 0 0 Y 0 0 Z 0 0 Return now to the General dialog page Define Type as Inlet Click on ATTRIBUTES and set velocity in x direction to 10 0 m s Click on OK to close the Object Attributes menu and on OK in the Object dialog Box f Next an outlet from the flow domain will be created To create an outlet from the domain Note The inlet object should already be selected now because settings have just been made for it If however it is not then click once on its image in the editing window or OMP to select it Click on the Duplicate object or group button the OK to allow the duplication There should now be two identical inlet objects the original hiding under the copy i e the copy is currently selected Click the X position up button until the copy of the inlet has moved right to the other end of the domain Now rename it and redefine it as an outlet by double clicking on it in the graphics window and in its Object dialog Box Change the name to OUTLET Then Define TYPE outlet Click on ATTRIBUTES and leave the default values as found Click on OK Go to the dialog page titled Place Set the position of object as X tick At end Y 0 0 Z 0 0 The final geometry should appear as in figure 1 Note the pin on the inlet object This is a flow direction indicator Flow travels along the shaft of the pin towards the head In this case it shows that flow is entering the domain from the left as expected g To set the solver parameters Click on Main menu on Numerics then on Total number of iterations Set the number of iterations also called sweeps in this window to 200 Click on Top menu Click on OK h Next a point in the flow domain should be set where the flow variables can be probed or monitored as the solution runs To set the monitor location Click on the probe icon on the toolbar or double click the probe itself and move the probe to X 0 5 Y 0 5 Z 0 25 The monitor point is shown as the pencil probe It can also be moved interactively with the X Y Z position up and down buttons as long as no object is currently selected i Check the grid Click on the Mesh toggle button The default mesh will appear on the screen Figure 13a The default grid As was mentioned earlier this mesh is good for the first few runs when trends can be established It should eventually be refined for a more accurate solution Running the example The PHOENICS solver is called Earth To run Earth click on Run then Solver then click on OK to confirm running Earth These actions should result in the PHOENICS Earth screen appearing As the Earth solver starts and the flow calculations commence two graphs should appear on the screen The left hand graph shows the variation of pressure and velocity at the monitoring point that was set during the model definition The right hand graph shows the variation of errors as the solution progresses Figure 14 is an example of these graphs from a typical EARTH solution sequence Figure 14 An example of an EARTH run screen As a converged solution is approached the values of the variables in the left hand graph should become constant With each successive sweep number the values of the errors shown in the right hand window should decrease steadily Runs can be stopped at any point by following the procedure outlined below Press any character key Click on Endjob Wait while the solver completes the current iteration and writes out the results files Please note If the solver is stopped before the values of the variables in the left hand graph of the convergence monitor approach a constant value the solution may not be fully converged and the resulting flow field parameters which have been calculated may not be reliable The VR Viewer The results of the flow simulation can be viewed with the PHOENICS VR post processor called VR Viewer This section provides a brief introduction to the capabilities of the VR Viewer What the VR Viewer can do In the VR Viewer the results of a flow simulation are displayed graphically The post processing capabilities of the VR Viewer that will be used in this example are vector plots contour plots iso surfaces surface contours streamlines line plots How to access the VR Viewer To access the VR Viewer simply click on the Run button then on Post processor then GUI Post processor VR Viewer in the PHOENICS VR environment When the File names dialog appears click OK to accept the current result files The screen shown in figure 15 should appear Figure 15 The VR Viewer screen for this case VR Viewer hand set The VR Viewer screen picture and hand set control buttons At first glance the VR Viewer looks very similar to the VR Editor There are however differences in the controls and graphics window annotations that allow the viewing of results in the flow domain for example To the left of the graphics window appears a coloured list of numbers This is the colour scale which corresponds to the currently selected result variable The colours associated with the numeric values on the scale are those that will be used when plotting flow vectors contour plots iso surfaces and streamlines A results probe can be used to query the flow domain for values of any selected result variable that has been solved for with the Earth solver The single number that appears at the top right of the viewing window indicates the value of the selected results variable at the current probe position The current probe position is indicated in the graphics window by the red pencil like probe icon The probe position can be changed by using the probe position arrows located in the lower portion of the larger handset These probe position controls work much like the position controls that were used to position objects in our earlier example in the VR Editor section of this document The probe can also be moved by clicking on the probe icon on the toolbar or double clicking the probe itself and using the dialog that appears A black rectangle cuts through the flow domain This rectangle indicates a results viewing plane that passes through the probe location If the background colour is dark the outline of the viewing plane will be white Flow vectors and results contours can be plotted on this viewing plane The orientation of this viewing plane can be changed by using the three viewing plane control icons marked X Y and Z located toward the centre of the control panel Once an orientation for the viewing plane has been chosen the Probe position controls can be used to move the probe and the associated viewing plane through the flow domain Vectors contours and iso surfaces can be plotted by using the three icons located to the left of the viewing plane control icons Vectors contours and iso surfaces are all coloured by reference to the current variable The value used for iso surfaces is the value of the current variable at the probe position Thus moving the probe will cause vectors contours and iso surfaces to be redrawn appropriately Streamlines can be plotted up or downstream or in both directions from the current probe position Multiple streamlines can be created by started along a line or around a circle A brief description of the control buttons of the VR Viewer is shown in figure 16 Figure 16 The viewing controls of the VR Viewer hand set These icons can be made to appear on the toolbar if the Viewer hand set is closed Viewing the results with VR Viewer The simple flow simulation just completed can now be viewed by obeying the following instructions Start by selecting Y as the viewing plane by clicking on the Slice direction Y button Now click on the Select velocity button followed by the Vector toggle This will display velocity vectors on the current result plane Use of the probe Y position arrow buttons will shift the location of the result plane along the y axis Pressure contours can be viewed by first clicking on the Vector toggle to turn off the vector display mode and then clicking on the P Select pressure button to set the current results variable to pressure Next click on the Contour toggle Contours of pressure are then displayed on the current result plane A velocity iso surface can be obtained by first clicking on the Contour toggle to turn off the plane of contours and then by clicking on the V Select velocity button followed by clicking on the Iso surface toggle This will display a surface of constant velocity known as an velocity iso surface The value of the iso surface will be the velocity which exists at the current probe position To obtain iso surfaces of different velocity values the position of the probe will need to be adjusted Typical displays of a vector contour and an iso surface plot are shown below in figures 17 a c respectively Figure 17a A typical vector plot Figure 17b A typical contour plot Figure 17c A typical iso surface Now experiment further with the rest of the control buttons so as to learn how to zoom in and out rotate etc To see the velocity distribution on the surface of the middle cylinder CYL 3 click on it to select it Right click to show the context menu and select Surface contour Click on the graphics window background to de select CYL 3 The surface contour should appear as in figure 17d Figure 17d Surface Contour of Velocity To display a tube of streamlines change the plotting plane to X by clicking on the Slice direction X button Move the probe nearer to the inlet around X 0 095 Click on the Streamline button to bring up the Streamline Management dialog The first time the Streamline dialog is opened it will go straight to the Options dialog In the section Streamline start click on the radio button Around a circle A small circle of spheres will now appear around the probe These represent the starting locations for the streamlines Click on OK to close the dialog Now choose the Object menu item New on the Streamline Management dialog which will generate a circle of streamlines as shown in figure 17e Figure 17e A Circle of Streamlines To return to the Options dialog at a later time select Object Options from the Streamline management Dialog To get a graph plot of a variable along a line click the Plot variable profile button on the toolbar On the dialog which appears enter the start and end coordinates of the line Enter how many points to plot and select the variable as shown in fig 17f Figure 17f The Graph options dialog When all entries are correct click Plot and the graph of the selected variable along the chosen line will appear as in fig 17g Figure 17g Pressure along the selected line Printing from VR Screen images such as figures 17a c can be sent directly to a printer by clicking on File then on Print from the main environment screen A dialog similar to that shown in figure 18a opens Figure 18a Print Dialog Box Alternatively the screen image can be saved to a file by clicking on File then on Save window as from the main environment screen When Save window as has been pressed the dialog box shown in figure 18b opens Figure 18b Save Window as Dialog Box The Save as file dialog offers a choice between GIF PCX BMP and JPG file formats and allows the image to be saved with a higher or lower resolution than the screen image The graphics files are dumped in the selected folder directory with the given name In all cases the background colour of the saved image is that selected from Options Background colour from the VR Editor main environment screen Saving the input and output files Before experimenting further attention should be paid to the following Any changes made in the VR Editor will overwrite the input files Likewise any re runs of the EARTH solver will overwrite the output files Therefore you may want to save these files more permanently To accomplish this click on File then on Save as a case This opens the dialog window shown in figure 19 Figure 19 Save as a case Dialog Box All the files associated with the current simulation are

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  • TR/326: PHOENICS-VR Reference Guide
    sources between calculations Clipping plane 3D graphically clips the image No effect on solution Plot surface 2D or 3D provides surface for contour or vector plots in Viewer No effect on solution InForm Commands Many objects types have a button labeled InForm Commands on their attributes page This leads to a dialog from which a selection of InForm commands can be attached to this object It is described in here Importing CAD Data This section describes how to import CAD data from STL or DXF format files Introduction Allowable Geometries Importing a Single CAD Object Assembling a Complete Geometry Translation Errors Treatment of Solid Fluid Boundaries PARSOL The VR Editor allows irregular geometries to be attached to rectangular objects Within the solver Earth the intersections of the geometry with the grid lines are calculated By default the Earth solver uses an accurate representation of the true geometry This is the Partial Solid method PARSOL In this method sometimes known as a cut cell technique the areas and volumes of partially blocked cells are calculated to a high degree of accuracy and the equation formulation is modified to account for the local non orthogonality Fine grid volumes can be used to increase the mesh density near a surface and thus improve the resolution still further PARSOL works in Cartesian and Cylindrical Polar co ordinates but is not available for BFC geometries The PARSOL method can be de activated by setting Partial Solids Treatment to be OFF in the Geometry panel of the Main menu Sloping or curved surfaces are then represented in a stair case fashion If the centre of a cell falls inside a solid the entire cell is taken to be solid If it falls in the fluid the entire cell is open to flow In many cases such an approach will provide entirely satisfactory results In some cases however such a representation is inadequate and will result in unacceptable loss of pressure The first image shows a flow through a turn around duct with PARSOL turned off the second with it turned on IMAGE Without PARSOL IMAGE With PARSOL The case in question is Library case 804 Default Geometries When an object is first created and a type is selected one of the following dat files will be used as the default geometry Object Type Cartesian Grid Polar Grid Blockage solid Cube14 grey Polcu8 grey Blockage solid heat Cube4 red Polcu7 red Blockage fluid Cubet transparent grey Polcubt2 transparent grey Blockage fluid heat Cubet1 transparent red Polcubt1 transparent red Inlet Angled in Cube3t transparent purple Polcu5t transparent purple Outlet Angled out Cube12t transparent light blue Polcubet transparent light blue Plate Cube11 light brown Polcu10 light brown Plate heat Cube13 orange Polcu2 orange Thin plate Cube11 light brown Polcu10 light brown Foliage foliage transparent light green foliage transparent light green Fan Cube2t transparent white or Cylpipe if circular Polcu4t transparent white Point history Default khaki Poldef khaki Fine grid volume Fine special wire frame Polfgv User defined 1 Default

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  • WELCOME to POLIS, the PHOENICS On-Line Information System
    Winter 2015 Flash Version of Latest News Letter WELCOME to POLIS the PHOENICS On Line Information System What POLIS consists of Some other places to look for information PHOENICS Overview What s new in PHOENICS PHOENICS related lectures and tutorials Major documents Application Examples Index to the PHOENICS Encyclopaedia Entries of especial interest In Form data input via formulae MIGAL the Multi Grid solver MOFOR MOving Frame Of Reference PARSOL

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  • TR314: CVD User Guide
    The Kleijn model for silicon deposition is represented by reactions 6 7 9 10 16 select these and return to the menu As surface reactions are included we must define the surfaces on which they occur this will be done later when the geometry is being defined We will now set a relaxation patch based on the chemistry in addition to the flow based relaxation already activated click in the tick box by Activate relaxation patch to activate the patch The default factor of 0 5 is satisfactory so return to the main CVD panel Geometry and boundary conditions At this point we need to create the geometry so click Previous panel to return to the Top menu then OK to leave the menu Turn the mesh toggle on and click in the domain to bring up the Mesh Settings dialog Switch to cylindrical polar co ordinates and set the domain size to 0 01 radians in X 0 21m in Y and 0 34m in Z Leave the grid set to AUTO in all directions Close the Mesh Settings dialog The next task is to set up objects to which initial or boundary conditions will be attached in the ASM geometry we need to identify solid regions FIN WAFER blank regions BL1 BL2 inlet outlet wall and wafer as shown in the diagram To create the objects click on Object on the hand set or on the toolbar to bring up the Object Management Dialog On the menu bar of that dialog click Object New New Object Set name to BL1 Set Size and Position as 0 01 0 155 0 1 0 0 0 0 0 24 Click General then Attributes Leave the material as the default Solid with smooth wall friction The volume covered by this object will be blanked out of the solution Set a surface temperature of 290K on the North and Low faces Click OK to close the Attributes dialog and OK to close the Object Specification dialog Click Object New New Object Set name to BL2 Set Size and Position to 0 01 0 11 0 1 0 0 0 1 0 0 Set a surface temperature of 290K on the South and High faces Click OK to close the Attributes dialog and OK to close the Specification dialog Click Object New New Object Set name to FIN Set Size and Position to 0 01 0 005 0 04 0 0 0 1 0 1 In General Attributes change the material to 111 Steel Click on Other materials select Solids then 111 Steel at 27 deg C Click OK to close the Attributes dialog and OK to close the Specification dialog Click Object New New Object Set name to WAFER Set Size and Position to 0 01 0 12 0 005 0 0 0 0 0 235 In General Attributes change the material to 111 Steel Activate Surface chemistry on the Low face Click CVD Settings Surface Chemistry Plasma then toggle No to Yes for the Low face Click OK to close the dialog Set the heat source to Fixed temperature of 900K Click on Adiabatic next to Heat source From the list of energy sources select Fixed Temperature then enter 900 in the Value input box Click OK to close the Attributes dialog and OK to close the Specification dialog Click Object New New Object Set name to INLET Set Size and Position to 0 01 0 1 0 0 0 0 0 0 0 0 In General set the Type to INLET In Attributes set the inlet density to user set 1 573E 3 kg m 3 the temperature to 290K the Z velocity to 1 344 m s and the inlet value of S140 SIH 4 to 0 113 Click OK to close the Attributes dialog and OK to close the Specification dialog Click Object New New Object Set name to OUTLET Set Size and Position to 0 01 0 055 0 0 0 0 0 155 0 34 In General set the Type to OUTLET Click OK to close the Attributes dialog and OK to close the Specification dialog Click Object New New Object Set name to WALL Set Size and Position to 0 01 0 0 0 24 0 0 0 21 0 1 In General set the Type to PLATE In Attributes set a surface temperature of 290K Click OK to close the Attributes dialog and OK to close the Specification dialog Title Click on Menu On the top page enter a suitable title for the case Initialisation Solution is made more efficient if realistic initial values can be specified for the solved variables In Initialisation set S116 N 2 to 0 887 S140 SIH 4 to 0 113 and TEM1 to 290 The initial values for the species equations must be in mass fractions not molar fractions Variables On the Models panel click on Settings by Solution control Extra variables This confirms that the correct velocity components pressure temperature and species are being solved it also shows the stored variables including the carrier species the deposition rate variable DEPO and PRPS to define material properties click Previous panel If additional variables were required this would provide the route for setting them Numerical Controls In Numerics set 400 sweeps The default relaxation settings will suffice Note plasma variables if active will usually require a very small setting of FALSDT This is because they are unaffected by the gas flow that normally determined the appropriate relaxation level Radiation Go to Models CVD Radiation Settings The optical property temperature determines the temperature at which the properties will be calculated Set the default reference temperature for optical properties to 290K The optical property index defaults to 198 which represents black body In this case the outer walls are steel which has an index of 111 Change the default material for optical properties to 111 Steel spectral set equal to iron The default setting for an outside zone is Fixed heat flux of 0W adiabatic Change this to Fixed temperature and set the default external temperature to 290K Activate radiation 12 radiation surfaces should be created each using the set default values It will be necessary to modify some of these later Leave the CVD menu and the Main Menu In the Object Management Dialog select all the blockage plate inlet and outlet objects and hide them The radiation surfaces will now be visible It may help to go to Settings Editor parameters and increase the X scale factor to 10 Select the 3 surfaces which cover the FIN object B10 12 and from the right click context menu open the dialog box In Attributes change the optical property temperature to 300 Close the dialog and click YES to propagate the change Select the 2 surfaces covering the WAFER object B13 14 and in the same way change the optical property temperature to 900 Monitoring controls The print out controls can be left at their default settings but it is sensible to match the monitoring probe location to the problem While the code is running the values of selected variables in the monitoring cell will be displayed It is worth selecting a sensible cell for the probe which will provide useful information on the progress of the solution Move the probe to 0 005 0 05 0 16 The Position buttons on the hand set move the probe when no object is selected Solution Run the solver by clicking on Run Solver The solution should look something like this in the VR Viewer post processor This example has demonstrated the general use of the menu There are many more options that have not been used and you might like to investigate them further It is advisable to save the q1 file just created before doing so click File Save as a case and enter a descriptive case name All the input and output files will be saved using the given name as a base The q1 input file In this section the q1 settings required to activate the different model options are described a working knowledge of the PHOENICS Input Language is assumed Sample q1 files are included in the CVD Input Library and should be referred to in conjunction with the descriptions below The first corresponds to the same problem as used for the menu description above but it was created without using the menu experienced PHOENICS users might like to compare it with the q1 file created by the menu and convince themselves that the two although different in format are equivalent in content The CVD options are activated by setting NAMGRD CVD this line should therefore always be included Variables The primary variables are the mass fractions of the gas species These should be identified as scalar variables between C1 and C30 inclusive corresponding to integers 16 to 45 and it is essential that no other variables should occupy any of these allocations One and only one of the mass fractions should be stored rather than solved its value will then be deduced by the requirement that the mass fractions must sum to unity It is recommended that the dominant species in terms of mass or molar fraction should be the one to be stored the stored species will also be the one used internally if material properties are based on the carrier gas rather than the local mixture All solved species should be solved whole field by use of the SOLUTN setting Certain other variables must also be stored i the appropriate flow variables pressure P1 velocities U1 V1 W1 depending on problem dimensionality and temperature TEM1 ii material identifier PRPS and deposition rate DEPO in Angstrom minute Additional variable names are also recognised if storage is activated for them in the q1 file the appropriate values will be inserted automatically within the code and can then be printed in the result file or viewed using the VR Viewer post processor These are FR01 FRnn MD01 MDnn SP01 SPnn SN01 SNnn SPHT and KOND they refer to molar fractions for each species multi component diffusion coefficients for each species positive and negative gas phase chemistry sources for each species mixture specific heat and mixture thermal conductivity respectively Here nn is the total number of gas species Note that the molar fractions diffusion coefficients and sources will be in an internal order this will be different from the order used in the q1 file only if the first species named in the q1 file C1 is not the one that is stored rather than solved Care must be taken when using the optional storage to ensure that only species mass fractions occupy the positions 16 to 45 in the variable list Note that SPHT will contain an effective specific heat defined as h h0 T where h is enthalpy T temperature and subscript 0 refers to 250K The different gas species involved in the simulation must be identified using the NAME command The available species are listed in the data file SPECIDAT which can be modified to suit the user s requirements subject to a limit of 300 species and the proviso that the corresponding species must all appear in the transport and thermodynamics data files TRANSDAT and THERMDAT The name of a species is made up of S followed by the identifying number in SPECIDAT so S80 is hydrogen if the default SPECIDAT is used In the VR Editor The solution for pressure velocity temperature and all the selected species is activaed automatically by the Editor together with storage for DEPO and EMIS Storage of other derived variables such as the molar fractions can be activated from Main menu Models Solution control Extra variables Diffusion settings Settings are required in the q1 file to determine which of the various models will be used for multi component and thermal diffusion These make extensive use of the SPEDAT command the use of which can be understood from the q1 files provided and the examples below In the first case the choice is between Fick Wilke and Stefan Maxwell Multi component diffusion is activated by the PRNDTL command for the mass fraction variables the appropriate setting is GRND8 Model selection is specified by the variable MCDOPT using the SPEDAT command values of 1 2 and 3 respectively should be used For Stefan Maxwell diffusion it is often necessary to implement linear relaxation using SPEDAT to define the relaxation factor SMRLX The binary diffusion coefficient can be calculated using actual temperature or a reference value selected by values of 4 and 2 respectively for BINOPT again specified using SPEDAT if a reference temperature is required it must be allocated to TMP1A Thermal diffusion options also make use of SPEDAT to define THMDIF THMOPT and THMFRQ The first of these should be set to T to activate thermal diffusion the second determines the model to be used 1 Clark Jones form using rigid spheres approximation 2 Clark Jones form using Lennard Jones parameters 3 exact form using rigid spheres approximation 4 exact form using Lennard Jones parameters These are in increasing order of computation time as a computational economy it is possible to update the thermal diffusion source terms less frequently than every sweep by setting THMFRQ to a value greater than 1 Both Stefan Maxwell and thermal diffusion require the settings USOURC T and UDIFNE T these settings should anyway be made to include the energy transport caused by diffusion fluxes as should DIFCUT 0 0 Note that it is possible though not recommended to leave out these settings if neither Stefan Maxwell nor thermal diffusion is active in that case the energy flux associated with diffusion fluxes will also be omitted As an example the settings SPEDAT SET CVD MCDOPT I 3 SPEDAT SET CVD SMRLX R 0 5 SPEDAT SET CVD BINOPT I 4 SPEDAT SET CVD THMDIF L T SPEDAT SET CVD THMOPT I 3 SPEDAT SET CVD THMFRQ I 3 in addition to the appropriate PRNDTL USOURC UDIFNE and DIFCUT settings activate thermal diffusion based on the exact form using the rigid spheres approximation with source updates every three sweeps binary diffusion coefficient calculation based on actual temperature and Stefan Maxwell diffusion with a relaxation factor of 0 5 In the VR Editor The Editor makes all the above settings based on the choices made in the Diffusion panel of the CVD Menu Material property settings Material property settings are implemented by storing the variable PRPS and the specification of the selected property values in the q1 file Density RHO1 specific heat CP1 laminar viscosity ENUL and thermal diffusion coefficient PRNDTL TEM1 settings will then be taken from the property information table The commands FIINIT PRPS 70 and CSG10 q1 enable the user to specify this property information in the q1 file provided that property setting 70 has not been added to the props file in the PHOENICS d earth directory The following indented lines should then be included in the q1 file MATFLG T IMAT 1 70 GRND8 GRND8 GRND8 GRND8 1 000 0 0 0 0 0 0 0 0 The method to be used for the calculation of mixture properties is given by a SPEDAT command for the variable MCPROP 1 refers to the carrier gas at a reference temperature 2 to the carrier gas at actual temperature and 3 to the actual gas composition at the actual temperature Again TMP1A determines the reference temperature to be used if required One line of zeros should be included for each GRNDn entry in the property definition line Additional materials can also be specified here if IMAT is suitably increased In the VR Editor The Editor automatically inserts the material property lines for material 70 and makes it the domain material The mixture property settings are made based on the choices made in the Diffusion panel of the CVD menu Chemistry settings Gas phase chemistry is activated by means of a PATCH which will normally cover the whole solution domain solid regions will be excluded automatically by the code The patch name should start with CHEM and the type should be VOLUME To allow for source linearisation both coefficient and value must be set to GRND1 COVAL statements are required for all species and the temperature TEM1 Surface chemistry is activated by means of a PATCH having a name that starts with SURF note that there must be at least one additional character the patch type should be the appropriate area e g SOUTH and the patch should only extend over the gas cells adjacent to the solid surface COVAL statements should be provided for all species including those that are not involved in the surface reactions TEM1 and P1 this ensures that the Stefan velocity flux to the surface is correctly included The coefficient should be set to FIXFLU and the value to GRND1 in all cases except P1 there the coefficient should be set to the batch factor For a conventional surface chemistry patch this will be 1 0 A higher number can be used if the computational surface represents several physical surfaces by this means a batch reactor can be approximately simulated without modelling each wafer individually useful if a parametric study is being undertaken for which run times would otherwise be unacceptable If the coefficient is given an inappropriate setting e g FIXFLU a batch factor of 1 0 will be assumed Automatic under relaxation based on the chemistry sources can be useful in avoiding convergence problems caused by strong chemical reactions this is introduced by means of a PATCH called RELT having PHASEM type COVAL statements should be provided for all species involved in the chemistry with a coefficient of GRND1 and a value of SAME A linear relaxation factor CHMRLX can then be specified using SPEDAT values are between 0 and 1 with low values signifying tight relaxation Note that conventional relaxation may also be needed particularly for any species that do not participate in the chemistry Linear relaxation is recommended for TEM1 and a small value say 0 3 may be necessary to ensure stability The reactions to be included in the simulation are specified using their identification numbers in the CHEMIDAT data file additionally the total number of gas phase and surface reactions NGREAC and NSREAC respectively must be given In all cases SPEDAT is used The individual reaction numbers are specified using GREAC and SREAC in the two cases As an example SPEDAT SET CVD NGREAC I 2 SPEDAT SET CVD GREAC 1 I 6 SPEDAT SET CVD GREAC 2 I 7 SPEDAT SET CVD NSREAC I 1 SPEDAT SET CVD SREAC 1 I 12 declares two gas phase reactions 6 and 7 and one surface reaction 12 An output file data is created by the code containing information about the species present and the reactions that have been selected This should always be checked for consistency any mass imbalance in a selected reaction will in any case cause the code to issue a warning message In the VR Editor The whole domain gas phase chemistry CHEM patch is created automatically by the Editor The surface reaction SURF patches are automatically generated from each BLOCKAGE and PLATE object based on the settings for the faces The relaxation patch is created if the relaxation option is selected on the Chemistry page of the CVD menu Radiation settings Radiation is implemented by setting S2SR T in the q1 file additionally it is necessary to provide storage for variable EMIS which is used internally to define surface optical properties To ensure that the correct surface to surface radiation formulation is used the q1 file should also contain the line SPEDAT SET CVD RADCVD L T The model is based on a surface to surface viewfactor approach i e it is assumed that the gas is transparent Thermal zones must be defined to cover all solid surfaces and viewfactors are then calculated between all pairs of thermal zones taking account of any semi transparent solid regions From these a radiation exchange matrix is calculated that fully defines the energy transfer between surfaces in terms of the surface temperatures which are calculated unless they are defined as fixed Each thermal zone requires PATCH and COVAL commands to define the location type and boundary conditions for the zone The patch names must start with RI the patch type must always be an area e g SOUTH For zones on the surfaces of solids for which conjugate heat transfer is being employed referred to below as internal surfaces the patch should be on the solid side of the surface otherwise for example at the domain edge the patch should be on the gas side of the surface For each thermal zone there must be a COVAL command for TEM1 the coefficient and value determine the type of thermal boundary condition Coefficient Value Boundary condition GRND1 2 GRND1 Zero applied heat flux internal surface GRND1 2 VAL Fixed heat flux of VAL external surface 0 0 VAL Fixed temperature of VAL external surface Zero applied heat flux is the only permitted setting for an internal surface External surfaces i e surfaces of non participating solids normally have a specified surface temperature or heat flux GRND1 2 indicates that either GRND1 or GRND2 can be used GRND1 is usually preferred although in some circumstances the less stable GRND2 can be more efficient In addition to its radiation patch a fixed temperature thermal zone should be accompanied by an appropriate laminar wall boundary condition for temperature in the conventional manner see examples the menu will do this automatically A COVAL command is also necessary for the variable EMIS at each thermal zone The coefficient determines the solid material according to the numbering system in the data file OPTICDAT The value if positive specifies a reference temperature which will be used to calculate optical properties a negative value is used to indicate the thickness of a semi transparent coating If a semi transparent coating is indicated the EMIS coefficient will determine the optical properties in the layer the optical properties of the background material will be determined by the PRPS value there it is therefore necessary to ensure that consistency is maintained between PRPS values and the material labels in the optical data file The temperatures specified for the surface property calculation can only be a guess before the run has been carried out for the highest accuracy it would be necessary to carry out additional runs for which the thermal zone temperatures are taken from the result file for the preceding run these values are listed at the end of the result file Typically one or two continuation runs would be sufficient In order that the accuracy of the viewfactor calculation can be seen by the user two energy conservation checks are provided The first relates to the viewfactors themselves and the second to the radiation exchange matrix in each case the calculated value is printed out for each thermal zone to the screen and also to the output file rad dat see below together with the correct value Errors of more than 1 2 should be regarded with suspicion first check that the radiation patches have been correctly specified then try increasing the number of test rays used see below and then increase the number of thermal zones until satisfactory agreement is achieved In any case each thermal zone should be defined so that the surface temperature does not vary significantly over it An output file rad dat is created by the code in addition to information about the thermal zones that have been defined it contains the array of viewfactors between the thermal zones the accuracy checks referred to above and the radiation exchange matrix elements This file should be saved if further simulations using the same geometry and thermal zones are to be carried out It can then be renamed as RADI DAT if a file of that name is present in the current directory when a run is started the information it contains will be used and no viewfactor calculation will be carried out This can be a significant time saving feature but requires care Use of the wrong RADI DAT will usually cause an error because the number of thermal zones will be incorrect however if the number of thermal zones in RADI DAT is the same as that in the case being run the simulation will continue based on incorrect information If a second run is carried out using the same thermal zone definition but with differing surface properties it is possible provided that no semi transparent solids are present to use the previous viewfactor calculation as the basis for the derivation of the new radiation exchange matrix to achieve this it is necessary to modify rad dat to remove everything below the viewfactor array listing before renaming it as RADI DAT Several additional settings are available within the surface to surface radiation model these make use of the SPEDAT command XMIR YMIR and ZMIR are logicals which if set to T indicate symmetry in the corresponding co ordinate directions only available in 3 D AXIBFC enables a 2 D BFC case to be specified as axisymmetric By default the spectral variation of surface optical properties from OPTICDAT is used the constant values in the file can be chosen instead by setting NOSPCT to T In 3 D viewfactor calculations a coarse calculation is used in the construction of the viewfactors if an internal accuracy check is satisfied this can result in view factor symmetries being only approximately satisfied The logical FINE3D can be used to force the fine calculation under all circumstances this should restore the symmetries albeit at a cost in computation time The viewfactors are usually renormalised before the radiation exchange matrix is derived as a means of ensuring good energy conservation again this may remove certain symmetries and lead to small anomalies in the results VFNORM can be set to F to remove the renormalisation energy conservation will then be imposed by modifications to the radiation exchange matrix instead The accuracy of the viewfactor calculation can improved by increasing the number of test rays used in the determination of each zone to zone or cell to cell viewfactor the number of rays is specified using NUMRAY Note though that there is an internal limit of 5 and that NUMRAY has no effect in 3 D cases for which only one ray is used for each cell as a computational economy View factors in cyclic geometries can be calculated but only if BFC T If a polar grid is used it is necessary to carry out a preliminary calculation for which BFC T is set in the q1 file after the geometry has been defined the rad dat file can then be used as input for the real case BFC F as already described In the VR Editor The RI patches required to calculate the viewfactors are automatically generated from the RAD SURF objects which are themselves generated when the radiation model is turned on or whenever the Generate button is clicked on the Radiation page of the CVD menu The other additional settings described can be activated from the Other settings page of the CVD menu Radiation page Plasma settings If the plasma model is activated it is necessary to solve for an additional four variables T0 NE PHI1 and PHI2 these are respectively the electron temperature the electron density and the real and imaginary parts of the complex potential note that electron density is quoted in units of 10 16 electrons m 3 to avoid excessively large numbers As for the other scalar variables whole field solution should be activated Additional variable names are also recognised if storage is activated for them in the q1 file PHIT and GAMM are the amplitude and phase angle of the complex potential and GION is the ionisation rate The diffusive nature of the equations in the effective drift diffusion model requires the modification of the standard PHOENICS transport equations to remove the other terms this is achieved by setting TERMS N N Y P Y N for each plasma variable The diffusion coefficient is set by PRNDTL GRND7 in each case The source terms in the T0 and NE equations are set up using two patches which cover the whole domain solid regions being dealt with internally the patch names are COOL and IONIZE Each patch has type VOLUME and COVAL statements are required for T0 and NE in each case both coefficient and value should be set to GRND7 Other parameters in the plasma equations are specified using arrays T0PAR NEPAR and PHIPAR in SPEDAT statements the meanings are as follows NEPAR 1 Bohm velocity m 2 s NEPAR 2 Ionization rate upper bound on Arrhenius term s NEPAR 3 Ionization rate multiplying factor in Arrhenius term s NEPAR 4 Ionization rate activation energy in Arrhenius term K NEPAR 5 Ionization rate field independent rate m 3 s T0PAR 1 Ohmic heating coefficient m 2 K V 2 s T0PAR 2 Diffusion coefficient m 2 s T0PAR 3 Cooling source term time constant s T0PAR 4 Cooling source term equilibrium temperature K PHIPAR 1 Sheath parameter m 4 10 16 electrons PHIPAR 2 Electron mobility m 2 Vs PHIPAR 3 Phase angle of externally applied potential radians PHIPAR 4 Magnitude of externally applied potential V In addition to the terms in the plasma equations it is also necessary to specify appropriate boundary conditions For T0 no action is required this ensures zero energy flux across boundaries For the potentials patches will be required for electrodes and earthed surfaces all these patches should have the appropriate area type and COVAL statements for PHI1 and PHI2 with a coefficient of FIXFLU and value of GRND7 Electrode patches should have a name starting with ELE the externally applied potential referred to above will be applied there All other PHI1 and PHI2 patches of area type will be at zero potential corresponding to earthed surfaces NE boundary conditions should be specified at any surface through which electron flux is permitted The patch type should again be an area so the potential patches can be used for this purpose the coefficient for NE should be GRND7 and the value 0 0 Realistic initialisation for plasma variables can be very beneficial in particular an inappropriate value for T0 can have severe consequences because it is used in an exponential term in the electron density equation The plasma variables influence the chemistry and thus the flow however the flow only influences the plasma via the parameters in the plasma equations which are dependent on gas composition In the current release these parameters are taken to be constant and the plasma equations are then independent of the other variables It is therefore possible to solve for the plasma first in isolation and then restart with solution for gas species and flow variables once a reasonable plasma solution has been obtained This can be economical because no time is spent on the flow and chemistry solution while the plasma variables and thus the reaction rates are still unrealistic The use of linear relaxation for plasma variables can cause convergence difficulties when block correction is implemented False timestep is then recommended the appropriate value can be small typically O 10 6 In the VR Editor The solution for the plasma variables and the whole domain COOL and IONIZE patches are automatically created when the plasma model is turned on The appropriate boundary condition patches are created from BLOCKAGE and PLATE objects based on the settings made The parameters in the plasma equations are set from the Plasma settings pages of the CVD menu The plasma variables can be initialised from the Main menu Initialisation page Additional features To facilitate CVD modelling two additional features have been provided the first relates to inlets and the second to shower plates Inlets are normally defined in terms of mass flow per unit area with incoming velocity temperature and species mass fractions also being specified As an alternative it is possible to give the flow in terms of sccm standard cubic centimetres per minute over an area that must also be given the incoming gas composition must then be defined in terms of molar rather than mass fractions To select this option the patch name must begin with VIN COVAL statements are required for P1 and all other variables defining the incoming stream the coefficients are FIXFLU for P1 and ONLYMS for other variables as usual for an inlet The value for P1 is the inflow in sccm the value for the velocity normal to the inlet face is the corresponding area and the values for the gas species are molar fractions Thus PATCH VIN1 LOW COVAL VIN1 P1 FIXFLU 100 0 COVAL VIN1 W1 ONLYMS 0 1 COVAL VIN1 S80 ONLYMS 0 2 specifies an inflow of 100sccm over an inlet area of 0 1m 2 the gas composition is 20 S80 hydrogen by volume Note that this feature cannot be used in BFC cases Shower plates are common in CVD reactors and a special patch has been defined to model them The region in question should first be defined to have the appropriate solid properties using PRPS an additional patch should then be defined in the same place having a name beginning with SHWR and an area type that indicates the plane of the plate COVAL statements are required for all solved scalar variables in addition to the velocity component normal to the plate All values should be GRND7 and the coefficients should be ONLYMS with the exception of those for P1 and the normal velocity which have a special meaning The coefficient for the normal velocity should be the open area fraction porosity of the plate and that for P1 should be a loss parameter This is defined as dp dynamic viscosity x mean velocity where dp is the pressure drop across the plate for circular holes this will be equal to 32l a 2 where l is the thickness of the plate and a is the diameter of the holes As an example PATCH SHWR1 HIGH COVAL SHWR1 P1 32000 0 GRND7 COVAL SHWR1 W1 0 5 GRND7 COVAL SHWR1 S80 ONLYMS GRND7 COVAL SHWR1 TEM1 ONLYMS GRND7 CONPOR PLAT1 1 COVAL PLAT1 PRPS 0 0 111 represents a steel plate with 50 open area and a loss parameter of 32000 possibly representing a plate 1mm thick with holes of 1mm diameter Note that a new PRPS number should really be specifically defined so that the plate would have the properties that take account of its porous nature the two patches should cover the same range of cells The use of a stiff solver is possible for cases where the chemistry is much more important than the flow effects this can be activated by setting USOLVE T Using this approach involves solving for all species including the carrier the code will automatically make this adjustment but the user should ensure that all appropriate COVAL statements are provided for the species that is nominally stored such statements would not be needed under normal circumstances In the VR Editor The CVD sccm inlet using VIN as a patch name has not been implemented in the CVD menu The USER DEFINED object type can be used to create such a patch if required The shower plate has not been implemented as a special object type Again the USER DEFINED object can be used to create the patch commands listed above The stiff solver can be turned on from the Chemistry settings page of the CVD menu Summary of q1 settings This section contains a review of the settings described in the preceding sections Group 7 Variables to be solved or stored Flow variables including TEM1 Mass fractions C1 C30 one stored

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  • TR211: GENTRA User Guide
    Boundary conditions for particles 2 8 Numerical controls 2 9 Input Output controls 2 10 Ending the GENTRA Menu session 2 11 The GENTRA Library 3 Using GENTRA PIL 3 1 Introduction 3 2 The Q1 file generated by the GENTRA menu 3 3 GENTRA declarations 3 4 GENTRA Groups 1 to 4 GENTRA data 3 5 Provisions for the EARTH run 3 6 Transmission to EARTH 3 7 Exit and symmetry patches 4 Running GENTRA Earth 4 1 Introduction 4 2 The GENTRA run 4 3 Results produced by GENTRA 5 The GENTRA FORTRAN 5 1 Introduction 5 2 The structure of GENTRA EARTH 5 3 The FORTRAN subroutine GENIUS 5 4 The property function GPROPS 5 5 Building private versions of GENTRA 6 The GENTRA Equations 6 1 Introduction 6 2 The continuous phase equations 6 3 Lagrangian equations 6 4 Submodels 6 5 Integration of the equations 6 6 Additional information Appendix A Known Limitations of GENTRA Appendix B List of GENTRA PIL variables B 1 Introduction B 2 List of variables Appendix C List of GENTRA FORTRAN variables C 1 Variables for continuous phase C 2 Variables for particle phase C 3 Printout variables C 4

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